This invention relates generally to sewing machines, and in particular to a new and useful apparatus which can be added to existing sewing machines to increase productivity and to improve quality.
For the sewing of seams between linings and facing materials in the manufacture of jackets, novel and basic improvements over existing sewing machines are provided by this machine, including:
1. A plurality of automatic, pneumatically controlled fullnesses with preset rates which are inserted in predetermined segments of the seam. PA1 2. A positive feed system which automatically synchronizes the feed of piping being sewn into seams with the feed of the facing material, to assure evenness and smoothness in the seam with the piping. PA1 3. A pneumatic jet system for holding the material in place during the sewing of the last few stitches of the seam after the drag clamp has been released.
With regard to fullness, as is well known to those in the field, when two dissimilar materials are sewn into a seam such as the lining and facing of a jacket, the speed of the lining material must be increased relative to the speed of the facing material at various segments along the length of the seam to assure that the seam is even and flat. The relative difference in the speeds are referred to as "fullness."
For seams between the facing and lining materials for jackets, the fullness is often incorporated by an operator who manually pulls on the facing material while the seam is being sewn to slow down the speed of the facing material relative to the lining material. This type of operation requires highly skilled operators and often results in the lack of uniformity with regard to the quality of the seams in the jackets.
In some existing sewing machines, such as the 487G, a manual lever is used to set in a fullness. The fullness is actuated by the operation of a foot lever by the operator as the seam is being sewn. This system only allows for a single degree or amount of fullness for the seam. It does not result in the higher quality achieved by varying the fullness along the run of the seam more than once and at different degrees. In addition, the differences in timing between operators in applying the fullness and in the length of the segment to which the fullness is applied, results in varying the quality of the seams produced.
Sewing machines with speed controls which vary the relative speed between the top and bottom feeds to synchronize the speeds, and which use sensors and measuring wheels are disclosed in U.S. Pat. No. 3,954,071 (Mall et al.); U.S. Pat. No. 3,994,247 (Cummins); and U.S. Pat. No. 4,462,530 (Block et al.).
Devices which allow for variable rates of speed between the upper and lower feeds to change fullness are disclosed in U.S. Pat. No. 4,509,443 (Martell et al.) which programs a controller for sewing a seam to connect sleeves so that the operator merely has to feed in types of material and sizes onto a control panel to regulate the speed; U.S. Pat. No. 5,014,635 (Ochi et al.); and U.S. Pat. No. 4,867,082 (Sabbioni et al.) which uses a CPU, i.e., a central processing unit, to control speeds with a programmable microprocessor.
Sewing machines which automatically line up patterns for sewing seams are disclosed in U.S. Pat. No. 4,612,867 (Rosch et al.); U.S. Pat. No. 4,777,896 (Nomura); U.S. Pat. No. 4,867,087 (Suzuki et al.) and U.S. Pat. No. 4,898,110 (Nomura et al.).
Devices for inserting tapes or strips into sewing machines to sew to other material are disclosed in U.S. Pat. No. 4,951,586 (Becherini); U.S. Pat. No. 4,920,904 (Frye); U.S. Pat. No. 5,081,945 (Bozoglou); U.S. Pat. No. 4,998,965 (Easom); and U.S. Pat. No. 4,967,674 (Rohr et al.).
Various drag clamp devices are disclosed in U.S. Pat. No. 4,462,321 (Mall et al.) which discloses two drag clamps spaced laterally, the laterally spaced clamp holding a material in place after the first clamp releases; U.S. Pat. No. 4,258,637 (Hannemann) which discloses a pneumatically actuatable clamp; and U.S. Pat. No. 4,104,977 (Pollmeier et al.) which has a fixed clamp and a trailing clamp which are compressed-air operated.
U.S. Pat. No. 4,412,498 (Scholl) describes a differential feed device wherein the feed mechanisms are pneumatically controlled.
There is a need for a sewing machine which provides for greater automaticity and more uniform, higher quality in the sewing of seams between the lining and facing of jackets as does the machine of this invention. The sewing machine disclosed herein provides for approximately a 2.2 times increase in productivity in the sewing of jacket seams and a 3.2 times increase in the sewing of jacket seams with piping over existing machines. In addition to the productivity increases, an approximate 25% decrease in production rejects and lower quality seams is achieved.